Rare earth metals (e.g., La—Lu, Sc and Y) are critical components of technologies ranging from electric vehicles to personal electronics to advanced wind turbines. Globally, rare earth metals are produced primarily (nearly exclusively) by Chinese suppliers and their exports are controlled by the Chinese government through quotas. In the last 5 years, the Chinese government has consolidated its domestic production of rare earth metals and reduced exports resulting in global market instability. The instability has forced international suppliers to pursue (largely unsuccessfully) new sources for the elements. Recycling of rare earths from finished products is one possible new source; however, there is a shortage of simple chemical methods to enable recycling. Less than 1% of rare earths were recycled in 2011.
One of the most important uses of rare earth metals is in the manufacture of hard, permanent magnets. The most important and widely used rare earth magnet is neodymium iron boride: Nd2Fe14B (neo). The neo magnets may also contain amounts of the element praseodymium. In the manufacture of neo magnets, variable amounts of the elements Dy and/or Tb (depending on need) are added to improve the performance of the material over a wider temperature range. Dysprosium is one of the scarcest and most valuable of the rare earth metals and, because of its use in high performance neo magnets, its price is predicted to rise by 2600% in the next 25 years. The recycling of Dy and Nd from hard magnets has been identified as a potential source for those elements in a recently published life cycle analysis.
A key chemical problem for magnet recycling is the purification (separation) of dissolved Nd from dissolved Dy from a solution concentrate, following the chemically simpler removal of Fe and B. Current separations technology for rare earth metals uses countercurrent liquid-liquid extraction. This process is scalable, but is inefficient and requires significant initial capital investment and continuing costs in solvents and extractants.
Accordingly, a need exists in the field for new extraction and purification techniques that allow for the recovery and recycling of rare earth metals.